1. Field of the Invention
The present invention relates to a data embedding apparatus and a data embedding method which embed other data in media data, and a data extracting apparatus and a data extracting method which extract the embedded data.
2. Description of the Related Art
As a method of embedding other data in media data such as moving images, WO98/17061 discloses a method in which when media data is coded, the media data is divided into frames, and further, each of the divided frames is divided into a plurality of small regions. Thereafter, when coding modes are determined with respect to the respective small regions obtained through division, coding modes corresponding to information to be embedded are selected.
Extraction of information embedded by the above-mentioned embedding method from the media data is realized by outputting information corresponding to the coding mode which is obtained by decoding the media data.
However, in the conventional data embedding method, positions at which data have been embedded must be commonly utilized on the coding side and the decoding side. For instance, when embedding positions are changed for each of frames in the conventional data embedding method, an amount of embedding position specifying information is increased. As a result, there is a problem in that an entire data amount is increased.
Also, since embedding of data has been realized by causing the coding modes of the small regions to correspond to the embedding information, the embedding information largely influences the coding efficiency. Accordingly, there is another problem in that if the data amount of the embedding information is increased, the data amount of the media data is also increased.